Richard Krautheimer (1897-1994) fought for Germany in WWI but fled Germany when the Nazi racial laws dismissed Jews from the universities. After Rome, Louisville Kentucky and Poughkeepsie, Craig Smyth brought him to the IFA as a professor in 1952. The 500 words of English he brought with him across the ocean blossomed into eloquent English, perhaps best seen in the Ghiberti book. He retired from the IFA at age 75. His last seminar in 1971 was on Baroque Rome. About eight or ten Institute students took it but there were outsiders too, like Tod, John Pinto and me. All of us were deeply influenced by it; often friendships ensued with this gruff but warm and deeply cultured man. San Lorenzo fuori le mura in Rome and, after retirement, the Cancelleria courtyard were Krautheimer’s closest brushes with dirt, but more important was the way he imported the mind-set of archeology into art history. He set store on close, almost tactile observation and precise measurement. He believed in reconstruction of lost buildings and phases of buildings. The reconstructions in the Corpus are classics. Late in life he turned to urban history. Three Christian Capitals and Rome Profile of a City taught art historians how to become urban historians while The Rome of Alexander VII brought together the threads of our seminar. This talk aims to evaluate the Krautheimer effect on American architectural history as the field rapidly spins away from it.